Direct Laser Sintering Research Articles

Advancements in dental implant technology: the impact of smart polymers utilized through 3D printing

The field of dental implantology has witnessed significant advancements in recent years, driven by innovations in materials science and manufacturing technologies. One such innovation that holds promise for revolutionizing dental implant generation is the mixing of smart polymers thru three-D printing. This evaluation article affords a comprehensive overview of the effect of clever polymers in enhancing the performance and functionality of dental implants. We begin by using elucidating the fundamental residences of smart polymers, which include their stimuli-responsive conduct, biocompatibility, and mechanical strength. sooner or later, we discover the evolution and programs of 3ِD printing, e.g. like direct metallic laser sintering (DMLS) and selective laser melting (SLM), in dentistry, highlighting its position in fabricating custom designed dental implants. the combination of smart polymers into dental implants is discussed in element, overlaying surface modification techniques, incorporation of bioactive dealers, and customization for affected person-particular desires. furthermore, we look at how smart polymers make contributions to enhancing aspects such as osseointegration, peri-implantitis management, and average implant toughness. clinical insights and case studies are presented to illustrate the real-global applications and results of clever polymer-based dental implants. ultimately, this evaluation objectives to offer valuable insights for clinicians, researchers, and industry specialists worried within the improvement and utilization of advanced dental implant technologies.

Biological fixation of customized implants for post-traumatic acetabular deformities and defects

Introduction The number of surgical interventions using additive technologies in medicine has been growing both in Russia and with every year. Due to the development of printing customized implants, the use of standard (imported) designs has decreased by an average of 7 % in the provision of high-tech medical care. However, the issue of the pore size of customized implants for management of post-traumatic defects in the acetabulum remains open.Objective To evaluate the results of the treatment of patients with post-traumatic acetabulum defects and deformities with the implementation in clinical practice of customized implants with structure and size porous surface that are optimal from the point of view of biological fixation.Material and methods Porous implants with different types of porous structure were produced by direct laser sintering using Ti-6Al-4V titanium alloy powders. Experimental work was carried out in vitro to determine the ability of living fibroblasts to penetrate the pores of different sizes. Next, the clinical part of this study was conducted in order to determine the signs of biological fixation of customized acetabular implants in a group of patients (n = 30).Results The results of this experiment performed to analyze the penetration of living fibroblasts into the porous structure of implants with different pore size demonstrated that metal structures with a pore size of 400-499 μm can be singled out from all others. Discussion Analysis of the literature data shows that there is no consensus on the structure and size of the pores of a customized implant. In our work, we investigated the ability of human living fibroblasts to penetrate into the surface structure of a customized implant, as a result of which we determined their optimal pore size of 400-499 microns. It should be noted that this study was conducted for a definite anatomical location: the acetabulum. However, it cannot be excluded that the data obtained are relevant for other anatomical locations.Conclusion Management of bone defects in the acetabulum area with customized implants featuring the surface pore size of 400-499 microns is a justified and relevant method. A prerequisite for the use of such implants is strict compliance with the indications for their use, careful preoperative planning and correct positioning.

Spray drying as a one-step production method of SiC-based granulates for direct reactive laser sintering of Reaction Bonded Silicon Carbide (RBSiC)

This research is focused on the development and production of SiC-based granulates for reactive laser sintering. Ceramic slurries with different compositions of SiC, Si, C powders, and PVA binder were subjected to spray drying. Carbon source in form of latex was proposed to avoid a reaction of Si with H2O in alkalic pH caused by the presence of carbon in the slurry. It was observed that the latex was beneficial for improvement of the flowability. Selected granulates were subjected to laser processing using two different methods. The first one where SiC-based granulates were spray deposited on a SiC substrate and laser treated with single pulse working of the laser. The second method where a pressed green sample of SiC were processed by the continuous working mode of the laser. Results revealed that the use of the continuous work mode during laser processing allowed to produce Reaction Sintered SiC (RBSiC).

A Direct Laser Sintering Approach for the Electrophoretic Deposition Overlay of Yttria-Stabilized Zirconia on the Surface of a Thermal Barrier Coating System

The laser sintering process and modification of yttria-stabilized zirconia (YSZ) coatings subjected to electrophoretic deposition (EPD) on YSZ air-plasma-sprayed (APS) thermal barrier coatings (TBCs) were investigated. A Ni-based superalloy was plasma-sprayed using yttria-stabilized zirconia (YSZ) to create a thermal barrier coating with a 400 μm thickness. The electrophoretic deposition (EPD) technique was used to deposit the nanopowder of YSZ on the surface of YSZ TBCs. In this study, a technology based on the direct sintering of a green EPD layer using a laser beam was employed. The best conditions for the deposition overlay of the YSZ coating using a DC current were obtained with an applied voltage of 40 V, deposition time of 5 min, and suspension concentration of 10 g/L. Iodine was added to the solutions as a stabilizing agent. To overcome the problems of high sintering temperatures, laser sintering was adopted as a new approach. The microstructures of all the specimens were studied using field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS) analysis. Surface roughness was investigated using atomic force microscopy (AFM) analysis and the central line average (CLA). The direct laser sintering (DLS) process for the EPD overlay on the surface of the TBCs caused a reduction in surface roughness and porosity, and improvements in the microstructural and mechanical properties of the surface coatings were observed.

Impact of an Aluminization Process on the Microstructure and Texture of Samples of Haynes 282 Nickel Alloy Produced Using the Direct Metal Laser Sintering (DMLS) Technique.

In this study, we examined the effects of an aluminization process on the microstructure and texture of Haynes 282 nickel samples fabricated using the direct metal laser sintering technique. The aluminization process involved the use of chemical vapor deposition with AlCl3 vapors in a hydrogen atmosphere at a temperature of 1040 °C for 8 h. Following the 3D printing and aluminization steps, we analyzed the microstructure of the Haynes 282 nickel alloy samples using light microscopy and scanning electron microscopy. Additionally, we investigated the texture using X-ray diffractometry. A texture analysis revealed that after the process of direct laser sintering of metals, the texture of the Haynes 282 nickel alloy samples developed a texture typical of cast materials. Then, in the aluminization process, the texture was transformed-from foundry-type components to a texture characteristic of recrystallization.

Evaluation of the Retentive Forces from Removable Partial Denture Clasps Manufactured by the Digital Method

The purpose of this study was to evaluate the retentive forces over time of removable partial denture clasps fabricated by the digital method. Occlusal rest seats were fabricated on three premolar teeth fixed in acrylic blocks (9 × 20 × 40 mm). Digitization of the teeth was performed using a laboratory scanner (Zirkonzahn Scanner S600 GmbH, Gais, Italy). After the analysis and determination of the insertion axis, two types of clasps with mesial occlusal rests were designed per tooth: the back-action and the reverse back-action clasps, using the Partial Planner Zirkonzahn program. The file was sent for fabrication of six metal clasps from a cobalt-chromium SP2 alloy in the EOSINT M270 system by a direct laser sintering process. The Instron 5544 universal testing machine was used to perform 20,000 cycles of clasp insertion and removal in the corresponding tooth with a load cell of 100 N and a speed of 2.5 mm/s. The retentive force was recorded for each of the 1000 cycles, and the change in retention over time was calculated. Statistical analysis was performed using the nonparametric Mann–Whitney test and a significance level of 5%. At 16,000 cycles, a maximum change in retention of 3.74 N was recorded for the back-action clasps and a minimum of −24.28 N at 1000 cycles for the reverse back-action clasps. The reverse back-action clasps exhibited statistically significant lower change in retention than the reverse-action clasps at 4000 and 5000 cycles. No differences were observed in the remaining cycles. During the 20,000 cycles, the change in retention was low regardless of the type of clasp. For most cycles, there were no differences in the change in retention between the two types of clasps.

Investigation of spherical powder obtained by plasma spraying of wire from corrosion-resistant steel 03Kh17N10M2

At present, powder with spherical particles from corrosion-resistant steels is used in such widespread additive methods as selective laser melting, selective laser sintering, direct laser sintering, electron beam melting, and others. Each of these methods places high demands on the characteristics of the spherical particles of stainless steel powder. This article is devoted to the production of a spherical powder by plasma spraying of a wire with diameter of 1 mm from corrosion-resistant steel 03Kh17N10M2 and the study of powder characteristics on its suitability for the use in additive methods. The authors developed the technology for obtaining a spherical powder and studied the influence of spraying modes on the yield of fraction less than 160 μm, suitable for additive methods. With an increase in power and gas flow, the yield of fraction less than 160 μm increases and reaches more than 70 %. The resulting powder has high fluidity (17.6 ± 1 s), bulk density (4.15 ± 0.1 g/cm3 ) and density after tapping (4.36 ± 0.2 g/cm3 ) and is suitable for use in additive production. Influence of the spherical powder fraction on the fluidity, bulk density and density after tapping was also studied. The best characteristics were obtained for the –90 μm fraction: fluidity 16.64 ± 1 s, bulk density 4.16 ± 0.1 g/cm3 and density after tapping 4.38 ± 0.2 g/cm3. These figures meet the requirements for powders used in additive manufacturing, namely, the fluidity of 50 g of powder is less than 30 s and the bulk density is more than 3 g/cm3.

Design, Simulation, and Mechanical Testing of 3D-Printed Titanium Lattice Structures

Lattice structure topology is a rapidly growing area of research facilitated by developments in additive manufacturing. These low-density structures are particularly promising for their medical applications. However, predicting their performance becomes a challenging factor in their use. In this article, four lattice topologies are explored for their suitability as implants for the replacement of segmental bone defects. The study introduces a unit-cell concept for designing and manufacturing four lattice structures, BCC, FCC, AUX, and ORG, using direct melt laser sintering (DMLS). The elastic modulus was assessed using an axial compression strength test and validated using linear static FEA simulation. The outcomes of the simulation revealed the disparity between the unit cell and the entire lattice in the cases of BCC, FCC, and AUX, while the unit-cell concept of the full lattice structure was successful in ORG. Measurements of energy absorption obtained from the compression testing revealed that the ORG lattice had the highest absorbed energy (350 J) compared with the others. The observed failure modes indicated a sudden collapsing pattern during the compression test in the cases of BCC and FCC designs, while our inspired ORG and AUX lattices outperformed the others in terms of their structural integrity under identical loading conditions.

Direct selective laser sintering of high-entropy carbide ceramics

The direct selective laser sintering (SLS) process was successfully demonstrated for additive manufacturing of high-entropy carbide ceramics (HECC), in which a Yb fiber laser was employed for ultrafast (in seconds) reactive sintering of HECC specimens from a powder mixture of constitute monocarbides. A single-phase non-equiatomic HECC was successfully formed in the 4-HECC specimen with a uniform distribution of Zr, Nb, Hf, Ta, and C. In contrast, a three-layer microstructure was formed in the 5-HECC specimen with five metal elements (Zr, Nb, Hf, Ta and Ti), consisting of a TiC-rich top layer, a Zr–Hf–C enriched intermediate layer, and a non-equiatomic Zr–Ta–Nb–Hf–C HECC layer. Vickers hardness of 4- and 5-HECC specimens were 22.2 and 21.8 GPa, respectively, on the surface. These findings have important implications on the fundamental mechanisms governing interactions between laser and monocarbide powders to form a solid solution of HECCs during SLS.Graphical abstract

Evaluation of margin and internal fit of full arch metal coping fabricated using computer aided milling, direct laser sintering, and traditional casting technique

Evaluation of margin and internal fit of full arch metal coping fabricated using computer aided milling, direct laser sintering, and traditional casting technique

Direct laser sintering for lunar dust control: An experimental study of the effect of simulant mineralogy and process parameters on product strength and scalability

Dust is a hazard for lunar surface operations, and controlling lunar dust is critical to the operation of a permanent lunar base. The cost of importing materials from earth necessitates methods of dust control which use only in-situ materials. One such method is direct sintering, a process by which areas of the lunar surface are melted or sintered to seal the surface. Previous trials of solar, microwave and radiant direct sintering have produced mixed results, but direct laser sintering (DLS) offers a viable alternative. Lasers can be focussed to very high intensities, so a system power of a few hundred watts would be sufficient for DLS. In this study, almost 900 trials of DLS using a CO2 laser were conducted to investigate the influence of processing parameters and lunar dust simulant type on the physical and mechanical properties of DLS crusts formed on compacted simulants. A process parameter tuning method was implemented to maximise product mass, density, flexural strength and production rates while minimising energy requirements. Thereafter, strategies were developed by which a sintered crust of unlimited dimensions could be produced. The potential advantages of screening regolith prior to DLS were considered, and the impact of simulant type on the process was investigated. From the study, it was concluded that DLS was a viable method of dust control for un-trafficked or lightly trafficked areas and could be implemented by a small robot that could be accommodated within the payload of proposed Commercial Lunar Payload Services. Therefore, DLS has the potential to be the first ISRU dust control measure to be implemented on the moon.

Static and Fatigue Load Bearing Investigation on Porous Structure Titanium Additively Manufactured Anterior Cervical Cages.

This study investigates the static and fatigue behavior of porous and conventional anterior cervical cages. Porous structure titanium anterior cervical cages were manufactured using direct selective laser sintering technique. Four different types of cervical cages were designed and manufactured, among which three designs consist of porous structure (type 1, type 2, and type 3) and manufactured using metal 3D printing. Remaining one design (type 4) was manufactured using conventional machining and did not consist any porous structure. All types of manufactured cages were tested in compression under static and fatigue loading conditions as per ASTM F2077 standard. Static and fatigue subsidence testing was performed using ASTM F2267 standard. Static compression testing results of type 1 and type 4 cages reported higher yield load when compared to the type 2 and type 3 cages. Static subsidence testing results reported almost 11% less subsidence rate for additively manufactured cages than the conventional cages. Fatigue subsidence testing results showed that type 2 and type 3 cages can withstood approximately 21% higher number of cycles before subsidence as compare to the type 1 and type 4 cages. During fatigue testing, all the cages design survived 5 million cycles at the 3000 N loading. For 6000 N and 8000 N, loading rate type 2 and type 3 cages showed lower fatigue life when compared to other cages design. Since fatigue life of type 2 and type 3 cage designs were reported lower than other cages design, it is concluded that the performance of the additively manufactured porous cages can be significantly varied based upon the cage design features.

50 - Different Mechanical Properties of Sand Blasting on Co-Cr Alloys

The purpose of this in study was to determine the influence of the sand blasting on the microstructure and the mechanical properties of cobalt chromium alloys. Thirty Co-Cr metal substrates were fabricated according to ISO 9693-1, by Direct Melting Laser Sintering fabricating technique. One group of ten were sandblasted with 50μm Zinc oxide nanopowder, another group of ten were sandblasted with 250μm and one more group group of ten substrates were left as received without sandblasting at all. On the two fist groups a feldspathic porcelain was placed. Then the specimens were tested for metal-ceramic bond strength with 3-point bend test. The fractured specimens were observed with an optical and scanning electron microscopy in order to define the mode of failure. Also, X-ray diffraction spectroscopy was conducted to determine changes in crystalline phases after fabrication and the 3-point bend test. The first group of the 250μm gave more plasticity to the substrates and observed as more eslastic than th other two groups. The groups with the ceramic coating revealed cohesive bond strength. The metallographic analysis of the after porcelain firing, the after 3-point bend test specimens and the as-received revealed changes in microstructure. Regarding the crystallographic microstructure, the patterns had minor changes among the groups. The profilometry also indicated that the bigger the gridblasting particles made the surface of the substrates smother. The adhesion between the metal substrate and the ceramic layer is not affected by the sandblasting. All of the techniques showed similar results and the modulus of elasticity revealed that the bigger the particle of the sandblasting is the higher the mechanical properties are.

Коррозионностойкие стали в аддитивном производстве

This review discusses the main methods for producing spherical powder particles of corrosion-resistant steels as a material widely used in all industries. Also the examples of products made by modern additive methods are described. Currently, spherical powder particles of corrosion-resistant steels are used in the following additive methods: selective laser melting, selective laser sintering, direct laser sintering, and electron beam melting. Each of these methods has its own requirements for the characteristics of spherical powder particles of corrosion-resistant steels. The review provides a brief description of the principles of operation of each method and the requirements for spherical powder particles of corrosion-resistant steels. It also considers a detailed description of each method of additive manufacturing with a description of the principle of operation and specific examples of obtaining spherical particles of corrosion-resistant steel powders with indication of their properties (morphology, structural features, chemical composition, fluidity, bulk density). A comparative analysis was carried out with a description of disadvantages and advantages of each method. Examples of the use of spherical particles of corrosion-resistant steel powders for the manufacture of products by various additive methods (including post-processing) are given with description of the final products characteristics. Based on the data presented, a conclusion was made about the preferred methods for obtaining spherical particles of corrosion-resistant steel powders for specific additive methods used in modern industry. The review considers the following methods for producing spherical powder particles: water atomization (atomization of liquid metal with a jet of water under pressure); gas atomization (atomization of the melt with a jet of inert gas (argon or nitrogen) under pressure); centrifugal atomization (atomization of molten metal with a high-speed rotating disc); ultrasonic atomization (atomization of liquid metal by ultrasound); non-contact atomization (atomization of liquid metal with a powerful pulse of electric current); plasma wire spraying; plasma spraying of a rotating electrode; plasma spheroidization.

Investment casting with FFF (fused filament fabrication)-printed appliances: the intermediate step.

Some modifications of orthodontic appliances such as the rapid maxillary expansion (RME) device with a Hyrax screw or Herbst are fabricated using traditional investment casting (lost-wax casting). This is precise but very labor-intensive. New technologies enable us today to use direct selective laser sintering (SLS) to produce freeform metallic structures. These machines are very expensive and only available in specialized laboratories. The aim of this investigation was to combine fused filament fabrication (FFF) 3D printing with wax-based filaments to produce orthodontic appliances via investment casting. For demonstration purposes, a lingual arch, a palatal arch, and an RME appliance were digitally designed based on an intraoral scan. The *.stl files were sliced and printed with a dual-nozzle FFF printer. The object was printed with a wax-based filament especially suited for investment casting, and support structures were printed with water-soluble polyvinyl-alcohol (PVA) filament. The printed objects were cast in metal and finished. All appliances were successfully cast and polished. They were provisionally placed intraorally. The fit was clinically very good and comparable to traditionally crafted appliances. The printing and handling of the parts made of these special filaments is challenging. With this experiment, the successful production of investment casting using FFF printing was shown for the first time.

Laser-Induced Carbon Electrodes in a Three-Dimensionally Printed Flow Reactor for Detecting Lead Ions.

Nowadays, heavy metal pollution has attracted wide attention. Many electrochemical methods have been developed to detect heavy metal ions. The electrode surface usually needs to be modified, and the process is complicated. Herein, we demonstrate the fabrication of electrodes by direct laser sintering on commercial polymer films. The prepared porous carbon electrodes can be used directly without any modification. The electrodes were fixed in a 3D-printed flow reactor, which led to very little analyte required during the detection process. The velocities of the analyte under stirring and flowing conditions were simulated numerically. The results prove that flow detection is more conducive to improving detection sensitivity. The limit of detection is about 0.0330 mg/L for Pb2+. Moreover, the electrode has been proved to have good repeatability and stability.

Electrostatically assembled SiC–Al2O3 composite particles for direct selective laser sintering

In the advancement of directed energy deposition, 3D printing technology has been undergoing revolutionary changes, especially in metal and polymer printing technology. On the contrary, the 3D printing of ceramics has not experienced such rapid development due to their requirement for high-temperature sintering and inferior energy adsorption property, limiting their use in application such as direct selective laser sintering (SLS). In this study, a novel controlled fabrication of composite powders consisting of silicon carbide (SiC) and alumina (Al2O3) was developed for fundamental investigation in direct SLS using an infrared laser radiation with a wavelength of 915 nm. Improved laser absorbance and a plausible way to reduce volume shrinkage during the sintering process are demonstrated through the control of composite particles formation. The composite particles were designed using a bottom-up approach via an electrostatic nano-assembly method at room temperature. Although further finetuning is still indispensable prior to practical applications, the findings of this work will provide a vital platform for powder modification and advanced powder development for ceramic materials fabrication through directed energy deposition route.

Fabrication of Porous SiC by Direct Selective Laser Sintering Effect of Boron Carbide

Additive manufactured porous SiC is a promising material applied in extreme conditions characterised by high temperatures, chemical corrosion, and irradiation etc. However, residual Si’s existence deteriorates its performance and limits its application in harsh environments. In this study, B4C was introduced into the selective laser sintering process of SiC, and its effects on forming ability, pore parameters, microstructure, and phases were investigated. The results showed that when B4C was added, the processing window was enlarged. The minimum energy density was reduced from 457 J/cm2 to 214 J/cm2 when the content of B4C reached 15 wt%. Microstructure orientation was enhanced, and the residual silicon content was decreased from 38 at.% to about 8 at.%. Small pores were turned into large pores with the increase of B4C addition. The findings indicate that the addition of B4C increases the amount of liquid phase during the laser sintering process of silicon carbide, improving the SiC struts’ density and reducing the residual silicon by reacting with it. Therefore, the addition of B4C will help improve the application performance of selected laser-sintered silicon carbide under extreme conditions.

Direct selective laser sintering of hexagonal barium titanate ceramics

AbstractA direct selective laser sintering (SLS) process was combined with a laser preheating procedure to decrease the temperature gradient and thermal stress, which was demonstrated as a promising approach for additive manufacturing of BaTiO3 ceramics. The phase compositions in BaTiO3 ceramics fabricated by SLS were investigated by X‐ray and neutron diffractions. The surface morphologies and cross‐section microstructures were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A dense hexagonal h‐BaTiO3 layer was formed on the surface and extended to a depth of 500 μm, with a relative density higher than 97% and absence of pores or microcracks. SLS resulted in the formation of the high‐temperature phase, h‐BaTiO3, which was retained at room temperature possibly due to the high cooling rate. The grain boundaries of SLSed h‐BaTiO3 ceramics consist of a Ti‐rich secondary phase. Compared with that of the pressureless sintered t‐BaTiO3 ceramics, the Vickers hardness of SLSed h‐BaTiO3 is 70% higher.

Micro-Arc Zn- and Ag-Containing Coatings for Implants with Complex Porous Architecture Obtained by 3D Printing Method from Titanium Alloy

Relevance. The creation of porous three-dimensional materials for bone defects compensation and its subsequent regeneration is an important direction of medical materials science. The key issue in the interaction of an implant and bone tissue is the surface properties of the implant.The purpose of the study is to evaluate the physicochemical properties and compatibility of tissues of a living organism and porous implants with calcium phosphate Zn- and Ag-containing formed by microarc oxidation.Materials and Methods. Implants with various types of porous structure were made by direct laser sintering of titanium alloy Ti-6Al-4V powders. The calcium phosphate coatings, including Zn- and Ag-containing, were formed on the implants surface by microarc oxidation.Results. Coatings, deposited in electrolytes of various compositions, were uniformly distributed over the implants mesh structure. The phase composition of Zn-containing coatings, deposited in the acidic electrolyte, was represented by amorphous calcium phosphates. Ag-containing coatings, deposited in the alkaline electrolyte, had an amorphous-crystalline structure, the crystalline phase of which was identified as tricalcium phosphate in the α and β modifications. The samples of extracts of calcium phosphate Zn and Ag-containing coatings were co-cultured with pFb line of the human postnatal fibroblasts for 48 hours at 37°C in 5% CO2 atmosphere. The MTT test revealed a high metabolic activity of the co-cultured fibroblasts in comparison with the fibroblasts of control.Conclusion. The pFb line of the human postnatal fibroblasts retained their viability for 48 hours of co-culturing with calcium-phosphate Zn- and Ag-containing coatings. The tested product and its components did not negatively affect the cellular respiration. However, further studies are needed to determine the rate of bioresorption and the degree of antibacterial activity of calcium-phosphate Zn- and Ag-containing coatings.